Conventionally, inverter devices have been used which have a system interconnection function for converting input power from a DC power supply such as a solar battery or a storage battery to AC power and superimposing the converted AC power onto an AC system such as commercial power.
Such an inverter device includes a step-up circuit for stepping up voltage of input power, and an inverter circuit for converting output of a step-up circuit to AC power.
As such an inverter device, the following inverter device is proposed. Of a period in which AC power is outputted, the step-up circuit is caused to perform switching operation only during a period in which voltage of the input power supply is lower than an absolute value of AC system voltage, and switching operation of the step-up circuit is stopped during the other period, whereby loss due to switching in the inverter circuit and the step-up circuit is reduced and power can be outputted with increased efficiency (see, for example, Patent Literature 1).